Previous attempts to incorporate biocidal activity into materials and coatings have primarily involved two methods—1) physical mixing (blending) of biocides into the materials and coatings and 2) chemical binding of biocidal functional groups to the polymers or copolymers making up the materials and coatings. Chemical binding should be preferable for long-term biocidal activity if the bound biocidal functionality does not adversely affect the other desired properties of the material or coating, such as strength, appearance, and chemical resistance.
For example, a significant amount of work has been performed concerning rendering sponges biocidally active. This involves encapsulation of a variety of weak biocides into the porous structure of the sponge, either through physical blending or chemical bonding to the surface. The sponges modified in this manner can exhibit biocidal activity, but the contact times necessary for action are generally long, and some pathogens are not inactivated even at contact times of several hours.
Anti-fouling polyurethanes have been prepared by chemical incorporation of tributyl tin (as described, e.g., in U.S. Pat. No. 5,194,504) and quaternary ammonium salts (see, for example, J. Appl. Polym. Sci. 50: 663 (1993); J. Appl. Polym. Sci. 50: 671 (1993)). Coatings containing organo-tin compounds are being discredited as threats to the environment, and poly-quats are weak biocides which are nonregenerable. Thus, there is a definite need for more effective biocidal coatings and materials.
A new class of biocidal monomers and polymers known as N-halamines, which could be useful in producing biocidal coatings, has recently been developed. A non-toxic, non-irritating, and cost effective material named poly-1,3-dichloro-5-methyl-5-(4′-vinylphenyl)hydantoin, which is an inexpensive derivative of polystyrene, was first described in U.S. Pat. No. 5,490,983. Subsequent disclosures of its biocidal properties for use in disinfecting applications for water filters have recently occurred [see Ind. Eng. Chem. Res. 33:168 (1994); Water Res. Bull. 32:793 (1996); Ind. Eng. Chem. Res. 34:4106 (1995); J. Virolog. Meth. 66:263 (1997); Trends in Polym. Sci. 4:364 (1996); Water Cond. & Pur. 39:96 (1997)]. The polymer is effective against a broad spectrum of pathogens including Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Candida albicans, Klebsiella terrigena, poliovirus, and rotavirus, among others, causing large log reductions of pathogens with contact times on the order of a few seconds in water disinfection applications. N-halamine functional groups such as hydantoins, oxazolidinones, and imidazolidinones have also been employed recently in producing biocidal cellulose (U.S. Pat. No. 5,882,357), biocidal films on surfaces (U.S. Pat. No. 5,902,818), biocidal nylon (Lin, et al., J. Appl. Polym. Sci., 81,943 (2001)), and biocidal polyester (Lin, et al., J. Appl. Polym. Sci., 85, 177 (2002)); these patents and articles are hereby incorporated by reference for all of their teachings.
Almost two decades ago, Berger taught in U.S. Pat. No. 4,412,078 the composition and use of a series of alkyl and alkoxy silylpropylhydantoin derivatives as coupling agents for bonding glass fibers to organic resins and as self-bonding adhesion promoters for room-temperature curable silicone adhesives. Berger did not contemplate or teach the halogenation of such derivatives before or after bonding to a surface to render the surface biocidal.
Much work has been done concerning attaching quaternary ammonium functional groups, which are weak, nonregenerable biocides, to various silicon compounds which can then be bonded to surfaces to render them weakly biocidal, e.g., see, U.S. Pat. Nos. 3,560,385; 3,730,701; 3,794,736; 3,814,739; 3,860,709; 4,282,366; 4,504,541; 4,615,937; 4,692,374; 4,408,996; 4,414,268; and 5,954,869.
U.S. application Ser. No. 10/400,165 (publication U.S. 2004/0127667 A1) discloses the use of siloxane monomers and polymers containing N-halamine functional groups having an advantage over previous technology in biocidal efficacy in terms of both the required contact times and increased spectrum of activity against pathogens.
Work has been done previously on unhalogenated TTDD (7,7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decane-2,4-dione) and its derivatives (the monomeric starting material for the precursor N-halaminesiloxane monomers and polymers taught herein) for use in light and heat stabilization of polymers such as polypropylene (for example, see DE 76-2623464, DE 94-4407947, CAN 116:153052, EP 78-101720, JP 49061238, DE 72-2227689, FR 19670908, U.S. Pat. No. 4,322,522); however, none of these references contemplates or teaches the halogenation of this material or its derivatives before or after infusion into or bonding to a surface to render the surface biocidal.